Methods of catalyst activation

ABSTRACT

A method comprising preparing a multi-component catalyst system comprising a catalyst and a cocatalyst, and adjusting the level of at least one component of the catalyst system to maintain a user-desired level of catalyst activity throughout a process, wherein the component comprises a catalyst activator and wherein the catalyst activator comprises the catalyst or the cocatalyst. A method comprising contacting a polymerization catalyst system comprising a Ziegler-Natta catalyst and a cocatalyst with a catalyst activator at least twice during a polymerization process, wherein the polymerization process is carried out in a reactor system comprising multiple reactor types.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. patent application Ser. No.12/782,810, filed on May 19, 2010, which is a Divisional of U.S. patentapplication Ser. No. 12/272,113, filed on Nov. 17, 2008, now abandoned,the entireties of which are incorporated herein by reference.

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND

Technical Field

This disclosure relates to methods of improving the efficiency ofpolymerization processes employing multiple reactors. More specifically,this disclosure relates to methods of activating and/or maintainingcatalytic activity across a multi-reactor chain for the production ofimpact copolymers.

Background

Synthetic polymeric materials, particularly polypropylene resins, arewidely used in the manufacturing of a variety of end-use articlesranging from medical devices to food containers. Commercial gradepolypropylenes are typically produced using a Ziegler-Natta and/or ametallocene catalyst in a polymerization process. Many industries, suchas the packaging industry, utilize these polypropylene materials invarious manufacturing processes to create a variety of finished goods.

Impact copolymers are a rapidly growing segment of the market forsynthetic polymeric materials. In contrast to homopolymers, thesematerials consist of at least two monomers synthesized in such a fashionas to generate a final product having improved mechanical and/orphysical properties when compared to the homopolymer. For example, apolypropylene impact copolymer may be synthesized through the additionalcopolymerization of propylene and ethylene in a secondary reactordownstream of at least one reactor for synthesis of the polypropylenehomopolymer. Varying parameters, such as the reaction conditions in thesecondary reactor and/or the quantities of comonomer used may allow forthe production of a polypropylene impact copolymer tailored to meet theneeds of a wide-range of end-use applications. One drawback to theproduction of impact copolymers is the variation in production processefficiency due to the use of reactor systems comprising multiple typesof reactors. Thus, it would be desirable to develop a method ofproducing impact copolymers having an improved production processefficiency.

SUMMARY

Disclosed herein is a method comprising preparing a multi-componentcatalyst system comprising a catalyst and a cocatalyst, and adjustingthe level of at least one component of the catalyst system to maintain auser-desired level of catalyst activity throughout a process, whereinthe component comprises a catalyst activator and wherein the catalystactivator comprises the catalyst or the cocatalyst.

Further disclosed herein is a method comprising contacting apolymerization catalyst system comprising a Ziegler-Natta catalyst and acocatalyst with a catalyst activator at least twice during apolymerization process, wherein the polymerization process is carriedout in a reactor system comprising multiple reactor types.

Also disclosed herein is a method comprising contacting a propylenemonomer and ethylene comonomer with a catalyst system in a reactorsystem comprising a loop reactor disposed upstream of a gas phasereactor under conditions suitable to produce a polypropylene impactcopolymer, wherein a catalyst activator is introduced to the reactorsystem upstream of the gas phase reactor.

The foregoing has outlined rather broadly the features and technicaladvantages of the present disclosure in order that the detaileddescription of the embodiments that follow may be better understood.Additional features and advantages of the embodiments will be describedhereinafter that form the subject of the claims of the disclosure. Itshould be appreciated by those skilled in the art that the conceptionand the specific embodiments disclosed may be readily utilized as abasis for modifying or designing other structures for carrying out thesame purposes of the present disclosure. It should also be realized bythose skilled in the art that such equivalent constructions do notdepart from the spirit and scope of the disclosure as set forth in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-2 are embodiments of reactor systems.

FIG. 3 is a plot of the particle size distribution of the polymersamples from Example 1.

FIG. 4 is a plot of the bulk polymer yield as a function of the amountof TEAl added for the samples from Example 2.

FIG. 5 is a plot of the bulk polymer yield as a function of the[Al]/[Si] ratio for the samples from Example 2.

FIG. 6 is a plot of the bulk polymer yield as a function of the time inbulk for the samples from Example 3.

FIG. 7 is a plot of the particle size distribution for the polypropylenehomopolymer samples from Example 5.

FIG. 8 is a plot of the particle size distribution for the impactcopolymer samples from Example 5.

FIG. 9 is a graph of the ethylene content as a function of catalyst forthe samples of Example 7.

FIG. 10 is a graph of the percent xylene solubles as a function ofcatalyst for the samples from Example 7.

DETAILED DESCRIPTION

Disclosed herein are methods of improving the efficiency, for exampleproduction efficiency, of a process employing a multi-component catalystsystem. In an embodiment, a method of improving the efficiency of aprocess comprises preparing the multi-component catalyst systemcomprising a catalyst and a cocatalyst; and adjusting the level of atleast one component of the catalyst system to maintain a user-desiredlevel of activity throughout the reaction process. The component that isadjusted is hereinafter referred to as the catalyst activator. In anembodiment, the catalyst system comprises a Ziegler-Natta catalyst, acocatalyst, and optionally a second cocatalyst and/or an externalelectron donor. The catalyst activator may comprise a catalyst, acocatalyst, an external donor, or combinations thereof.

Herein, the catalyst activator functions to increase the activity of anactive catalyst system such that the catalyst system maintains auser-desired level of activity throughout the process. It is to beunderstood that the catalyst system, when formed, comprises multiplecomponents that are contacted in a predetermined amount and fashion toform a multi-component catalyst system, which collectively functions toaccelerate a process and possesses an initial activity that may decreaseover the course of the process. The catalyst activator may comprise oneor more of the components of the multi-component catalyst system.However, one of the catalyst activator's functions is to increase ormaintain some threshold level of activity of the catalyst system,whereas the catalyst system's primary function is to accelerate theprocess. Catalyst activators and methods of using same are described inmore detail later herein.

The catalyst system may be any catalyst system capable of having itsactivity increased by another material, and the catalyst activator maybe any material capable of increasing the activity of the catalystsystem. In an embodiment, the catalyst system comprises a ZN catalyst, acocatalyst, and optionally an external electron donor; and the catalystactivator comprises a catalyst, a cocatalyst, an external electrondonor, or combinations thereof. The catalyst system may be used toaccelerate a polymerization process, for example a process for theproduction of a polypropylene impact copolymer. In an embodiment, thepolymerization process may employ a reactor system comprising one ormore reactor types which is hereafter referred to as the reaction zone.An embodiment of a multi-reactor system for use in a polymerizationprocess is schematized in FIG. 1.

Referring to FIG. 1, the reactor system 500 comprises a feedstream 501to one or more reactors, such as a pre-polymerization loop reactor 510that is in fluid communication with the first bulk loop reactor 520 viaconduit 515. The first bulk loop reactor 520 may be upstream of and influid communication with a second bulk loop reactor 530 via conduit 525,which in turn is upstream up of and in fluid communication with one ormore gas phase reactors 540 via conduit 535. Various devices useful forthe polymerization processes disclosed herein, such as degasification,devolitization, compounding, and/or pelletization units, may be disposeddownstream from one or more of the reactors, e.g., from gas phasereactor 540, and may receive one or more effluent streams 545 from suchreactors for further processing.

A more detailed example of a bulk loop reactor system 10 suitable forpropylene polymerization using one or more catalysts of the typedisclosed herein (e.g., Ziegler-Natta catalysts) is illustrated in FIG.2. The bulk loop reactor system 10 includes a catalyst mixing andinjection system 200 upstream of and in communication with a pair ofloop reactors 300, a polymer recovery system 400 downstream of the loopreactors 300, and a gas phase reactor 500 receiving recovered polymerfrom recovery system 400. It will be understood that the bulk loopreactor system 10 may include a single loop reactor, a single gas phasereactor, multiple loop reactors, multiple gas phase reactors, or anycombination thereof, including one or more other olefin polymerizationreactors, such as other polymerization reactors. The bulk loop reactors300 may further include a propylene feed conduit 300B and a co-monomer(e.g., ethylene) feed conduit 300C. The catalyst mixing and injectionsystem 200 includes a mixing vessel 202. The mixing vessel 202 includesa mixing paddle 204 and a heating jacket 206. A high molecular weightoil, e.g., mineral oil, and the Ziegler-Natta catalyst may be introducedinto the mixing vessel 202. Generally the high molecular weight oil isheated to a sufficient temperature (in the range of from 30° C. to atleast 90° C., depending upon the type of oil used) in order to reducethe viscosity of the oil and allow the mixing paddle 204 to sufficientlymix the catalyst and high molecular weight oil. The heated mixture ofhigh molecular weight oil and catalyst is then conveyed via conduit 208to an injector 210 where it may cool and form a “paste.” The paste isurged during the compression stroke of a plunger 211 into a conduit 212and into another mixing vessel 214 wherein a co-catalyst, such astriethyl aluminum (TEAl), and optionally one or more electron donors maybe blended with the paste by the mixing paddle 216. The resultingmixture of catalyst, cocatalyst and optional electron donor exits themixing vessel 214 via conduit 218 and is metered by the pump 220 into apre-polymerization loop reactor 222 containing liquid propylene monomer.

Polymerization temperatures in the pre-polymerization loop reactor 222may be from between −10° C. and 40° C. and are controlled by coolingjackets 223. Polypropylene granules are formed as propylenepolymerization begins upon contact between the catalyst, co-catalyst,and optional donor and the liquid propylene monomer, all of which arecirculated within the pre-polymerization loop reactor 222 by acirculation pump 224. Pre-polymerization cycle time may last between 7and at least 30 minutes, alternatively between 15 and 20 minutes beforethe polypropylene granules are conveyed via conduit 226 into the firstloop reactor 302 containing liquid propylene monomer. A circulating pump304 circulates the polypropylene granules and liquid propylene monomerwithin the first loop reactor 302. As propylene polymerization continuesin the first loop reactor 302, the polypropylene granules increase insize. The first loop reactor 302 cycle time may last between 20 and atleast 95 minutes, alternatively between 30 and 50 minutes beforepolypropylene granules are conveyed via conduit 306 into the second loopreactor 308. Polymerization temperatures in the first and second loopreactors, 302 and 308 respectively, may range from between 60° C. to 80°C. and may be controlled by cooling jackets 310. Circulation pump 312circulates the polypropylene granules and liquid propylene monomer inthe second loop reactor 308. The second loop reactor 308 cycle time maylast between 10 and at least 60 minutes, alternatively between 20 and 50minutes before the polypropylene granules are conveyed via conduit 313into the polymer recovery system 400.

A heating column 402 receives the polypropylene granules from theconduit 313. Sufficient heat is applied to the polypropylene granulessuch that upon entering the flash tank 406 from the conduit 404, asubstantial portion of the liquid propylene monomer accompanying thepolypropylene granules vaporizes and thus separates from the granules.The gaseous propylene and a portion of the polymerization by-productsare extracted from the flash tank 406 via the conduit 408. This gaseouspropylene may be recompressed, filtered, to remove impurities and othercontaminants that may adversely react with the catalyst system (notshown), and returned to the loop reactors 300.

The polypropylene homopolymer recovered from polymer recover system 400may exit via a conduit designated reference arrow 410 and furtherprocessed. Alternatively, the polypropylene homopolymer may be subjectedto polymerization with one or more additional monomers, such asethylene. In such embodiments, the polypropylene granules exiting theflash tank 406 via conduit 412 may be conveyed into the gas phasereactor 500 where an additional monomer such as ethylene may beintroduced and the ethylene-propylene rubber (EPR) portion of the impactcopolymer generated. The polypropylene impact copolymer granules exitthe gas phase reactor 500 via conduit 502 and may be directed toextruders for processing into pellets. During the pelletization process,one or more other materials, such as, stabilizers, UV blockers,antistatic chemicals and/or pigments, may be blended with the polymergranules.

The catalyst activator may be introduced to the reaction zone at any orat various points in the reaction zone. For example, with reference toFIG. 1, the catalyst activator may be introduced to the reaction zone inthe prepolymerization reactor 510, reference arrow 550; after theprepolymerization reactor 510, at reference arrow 560, after the firstbulk loop reactor 520, at reference arrow 570, after the second bulkloop reactor 530, at reference arrow 580, in the gas phase reactor 540,at reference arrow 590; or combinations thereof. Referring to FIG. 2,the catalyst activator may be introduced to the reaction zone at one ormore of the locations such as for example, at loop reactors 222, 302, or308; at conduits 306 or 313; or at reactors 223 or 500. These locationsare not intended to be limiting as the disclosure includes any possibledistributed catalyst activator addition configurations.

In an embodiment, the catalyst activator may be introduced to thereaction zone continuously using devices that allow for the controlledaddition of the material at locations in the reaction zone of the typepreviously described. Devices suitable for the continuous controlledaddition of catalyst activators include for example and withoutlimitation metering systems such as mass flow controllers.Alternatively, the catalyst activator may be introduced to the reactionzone instantaneously as a single aliquot or complement of material.

In an embodiment, the catalyst system comprises a Ziegler-Natta (ZN)catalyst. ZN catalysts are stereospecific complexes formed from atransition metal halide and a metal alkyl or hydride. The ZN catalystsare derived from a halide of a transition metal, such as titanium orvanadium. The catalyst is usually comprised of a titanium halidesupported on a magnesium compound. ZN catalysts, such as titaniumtetrachloride (TiCl₄), supported on an active magnesium dihalide, suchas magnesium dichloride or magnesium dibromide, are described in theliterature for example in U.S. Pat. Nos. 4,298,718 and 4,544,717, eachof which is incorporated by reference herein in its entirety.

In an embodiment, the ZN catalyst may be used in conjunction with acocatalyst to form a catalyst system. Suitable co-catalysts may take theform of cocatalysts that are commonly employed in ZN polymerizationreactions. Thus, the cocatalyst can be generally characterized asorganometallic compounds of metals of Groups 1A, 2A, and 3B of thePeriodic Table of Elements. As a practical matter, organoaluminumcompounds are normally used as cocatalysts in polymerization reactions.Specific examples include triethylalumninum, tri-isobutylaluminum,diethylaluminum chloride, diethylaluminum hydride and the like.Activating cocatalysts normally employed may include methylalumoxane(MAO), triethylaluminum (TEAl), tri-isobutylaluminum (TIBAL), orcombinations thereof.

The cocatalyst may or may not be associated with or bound to a support,either in association with the catalyst component (e.g., ZN) or separatefrom the catalyst component, as is described by Gregory G. Hlatky,Heterogeneous Single-Site Catalysts for Olefin Polymerization 100(4)Chemical Reviews 1347-1374 (2000), which is incorporated by referenceherein in its entirety.

ZN catalysts may also be used in conjunction with one or more internaland/or external electron donors. An internal electron donor may be usedin the formation reaction of the catalyst. Thus, internal electrondonors are added during the preparation of the catalysts and may becombined with the support or otherwise complexed with the transitionmetal halide. Examples of internal electron donors include: amines,amides, ethers, esters, aromatic esters, ketones, nitrites, phosphines,stibines, arsines, phosphoramides, thioethers, thioesters, aldehydes,alcoholates, and salts of organic acids.

An external electron donor or selectivity control agent (SCA) may beused for stereoregulation in the polymerization reaction and may beadded during the polymerization process. Examples of external donorsinclude without limitation the organosilicon compounds such ascyclohexylmethyl dimethoxysilane (CMDS), dicyclopentyl dimethoxysilane(CPDS) and diisopropyl dimethoxysilane (DIDS). In an embodiment, theexternal electron donor may be present in an amount of from 0.5 ppm to300 ppm, alternatively from 1 to 150 ppm, or alternatively from 3 ppm to50 ppm based on the weight of propylene feed.

A description of the two types of electron donors is provided in U.S.Pat. Nos. 6,410,663 and 4,535,068, each of which is hereby incorporatedby reference herein in its entirety.

ZN catalysts are typically supported, and the support materials mayinclude talc, inorganic oxides, clays and clay minerals, ion-exchangedlayered compounds, diatomaceous earth compounds, zeolites, a resinoussupport material, such as a polyolefin, magnesium halides, magnesiumdihalides, such as magnesium dichloride or combinations thereof.Specific examples of inorganic oxides that may be useful supportmaterials include without limitation silica, alumina, magnesia, titaniaand zirconia. The inorganic oxides used as support materials may have anaverage particle size of from 10 microns to 600 microns or from 30microns to 100 microns, a surface area of from 50 m²/g to 1,000 m²/g orfrom 100 m²/g to 400 m²/g and a pore volume of from 0.5 cc/g to 3.5 cc/gor from 0.5 cc/g to 2 cc/g, for example. In an embodiment, the supportcomprises magnesium dichloride. In such an embodiment, the support mayhave an average particle size of from 5 microns to 100 microns,alternatively from 10 microns to 90 microns, alternatively from 20microns to 80 microns.

One of ordinary skill in the art with the benefits of this disclosuremay determine the effective amounts of each component of themulti-component catalyst system (e.g., catalyst, cocatalyst, externaldonor) to produce a desired result. The result desired (e.g., increasedproduct yield, increased production rate) will depend on the nature ofthe reaction process. The methodologies disclosed herein may result inan increased level of catalyst activity over the course of the reactionprocess, an increased level of catalyst activity at one or morelocations in the reaction zone or an increased level of catalystactivity at one or more intervals during the reaction process whencompared to the catalyst activity of a process carried out usingalternative methodologies.

The catalyst activator may comprise or consist essentially of one ofmore of the aforementioned components. In an embodiment, the catalystactivator comprises a cocatalyst. The cocatalyst may be of the typepreviously described herein. In some embodiments, the catalyst activatorand cocatalyst used to prepare the catalyst system are the samecompounds. Alternatively, the catalyst activator and the cocatalyst usedto prepare the catalyst system are different compounds.

In an embodiment, the catalyst activator comprises the cocatalyst. Insuch embodiments, the catalyst activator may be added to provide a totalamount of cocatalyst in excess of the amount normally employed in theprocess. Herein the amount normally employed refers to the amount ofcocatalyst used in an otherwise similar catalyst system and productionprocess not employing a catalyst activator. In embodiments not employinga catalyst activator the total amount of cocatalyst normally introducedto the reaction zone may be designated x. For example x may be from 50ppm to 400 ppm, alternatively from 100 ppm to 350 ppm, alternativelyfrom 150 ppm to 300 ppm based on the weight of propylene feed. In anembodiment, the catalyst activator comprises the same compound as thecocatalyst and the total amount of catalyst activator (i.e., cocatalyst)introduced to the reaction zone may be designated y. In suchembodiments, the total amount of cocatalyst introduced to the reactionzone may be greater than the total amount of cocatalyst introduced tothe reaction zone in an otherwise similar process not employing acatalyst activator. In other words y is greater than x. Alternatively yis 1.5 times greater than x, alternatively y is 2.0 times greater thanx.

In an alternative embodiment, the catalyst activator is the samecompound as the cocatalyst used to prepare the catalyst system however,the cocatalyst is present in an initial amount that is reduced incomparison to some “normal initial amount” of cocatalyst typically usedto prepare the catalyst system. For example, the cocatalyst may bepresent in a normal initial amount (z), however, when used as a catalystactivator, the cocatalyst may be present in a reduced initial amount (b)wherein b is less than z. For example z may be from 50 ppm to 400 ppm,alternatively from 100 ppm to 350 ppm, alternatively from 150 ppm to 300ppm.

In an embodiment, b is 20%, 25%, 30%, 35%, or 40% less than z. Forexample, the cocatalyst may comprise TEAl which may be present in areduced initial amount of from 90 ppm to 120 ppm (i.e., b) when comparedto a normal initial amount (i.e., z) of 150 ppm. Herein, the normalinitial amount refers to the amount of material present prior tocontacting the catalyst system with a monomer in a reaction zone underconditions suitable for the polymerization of said monomer.

A catalyst system comprising a reduced initial amount of cocatalyst bmay comprise an initial amount of catalyst that is increased whencompared to a “normal amount” of catalyst (n) that is initially presentin the system. For example, a catalyst system may comprise a reducedinitial amount of cocatalyst (b) and an increased initial amount ofcatalyst (k). In an embodiment, k is greater than n, alternatively k is10% greater than n, alternatively k is 20% greater than n, andalternatively k is 25% greater than n. The catalyst amount necessary tocompensate for the reduction in catalytic activity due to the decreasein the cocatalyst amount may, be determined by one of ordinary skill inthe art with the benefits of this disclosure. The resulting catalystcomposition comprising a reduced amount of cocatalyst (b) and anincreased amount of catalyst (k) may be introduced to a reaction zone asdescribed and catalyze the polymerization of an olefin as describedpreviously herein. In such embodiments, the initial amount of catalystpresent in the system may be increased to compensate for the reducedinitial amount of cocatalyst. Without wishing to be limited by theory,the reduced amount of cocatalyst (e.g., TEAl) may not fully activate thecatalyst resulting in an initial catalytic activity that is reduced whencompared to the initial catalytic activity observed in the presence of anormal amount of cocatalyst. In order to maintain a user-desiredpolymerization rate through some portion of the reaction zone (e.g.,FIG. 2, loop reactors 222, 302, 308), additional catalyst may beintroduced to the reaction zone.

In such embodiments, additional cocatalyst may be introduced to thereaction zone via one or more distributed additions and function as acatalyst activator to maintain a user-desired threshold of catalyticactivity as described previously herein. The amount of additionalcocatalyst introduced to the reaction zone and that functions as acatalyst activator may be denoted (m) wherein (m)+(b) equals (z).

In other words, in embodiments wherein the catalyst system comprises areduced initial amount of cocatalyst and an increased initial amount ofcatalyst, the total amount of cocatalyst introduced to the reaction zoneis equivalent to the normal amount of cocatalyst typically employed inthe reaction process. This additional amount of cocatalyst whenintroduced to the system may function as a catalyst activator. Thisadditional amount of cocatalyst, also termed a complement, may beintroduced to the reaction zone via the methodologies describedpreviously herein. For example, the complement of cocatalyst may beintroduced to the reaction zone at any appropriate location. Forexample, the complement of cocatalyst may be introduced to an upstreamreactor (e.g., loop reactor, FIG. 2 223, 302, 308) and provide aproductivity boost in the downstream reactors (e.g., GPR FIG. 2, 500)

In an embodiment, the process comprises a polymerization process such asthe production of polypropylene impact copolymer. Polypropylene impactcopolymers are bi-phasic polymers, wherein an elastomeric phase (e.g.,EPR) is dispersed as particles in a homopolymer phase or component(e.g., polypropylene homopolymer). The polypropylene impact copolymersmay comprise from 2 to 20 wt. % by weight ethylene, alternatively from 5wt. % to 15 wt. % alternatively from 8 wt. % to 12 wt. % based on thetotal weight of the copolymer. Herein, percentages of a component referto the percent by weight of that component in the total compositionunless otherwise noted.

The homopolymer phase of a polypropylene impact copolymers may be apropylene homopolymer, provided that the homopolymer phase may containup to 5% of another alpha-olefin, including but not limited to C₂-C₈alpha-olefins such as ethylene and 1-butene. Despite the potentialpresence of small amounts of other alpha-olefins, this is generallyreferred to as a polypropylene homopolymer.

The copolymer phase of a polypropylene impact copolymer may be a randomcopolymer of propylene and ethylene, also referred to as anethylene/propylene rubber (EPR). Without being limited by theory, theEPR portion of the polypropylene impact copolymer has rubberycharacteristics which, when incorporated within the matrix of thehomopolymer component, may function to provide increased impact strengthto the copolymer. In an embodiment, the EPR portion of the polypropyleneimpact copolymers comprises from 10 wt. % to 30 wt. % of the copolymer,alternatively 30 wt. % of the copolymer, alternatively 20 wt. % of thecopolymer, alternatively 10 wt. % of the copolymer.

The amount of ethylene present in the EPR portion of the polypropyleneimpact copolymer may be from 30 wt. % to 60 wt. %, alternatively from 35wt. % to 55 wt. % based on the total weight of the EPR portion. Theamount of ethylene present in the EPR portion of the copolymer may bedetermined spectrophotometrically using a Fourier transform infraredspectroscopy (FTIR) method. Specifically, the FTIR spectrum of apolymeric sample is recorded for a series of samples having a known EPRethylene content. The ratio of transmittance at 720 cm⁻¹/900 cm⁻¹ iscalculated for each ethylene concentration and a calibration curve maythen be constructed. Linear regression analysis on the calibration curvecan then be carried out to derive an equation that is then used todetermine the EPR ethylene content for a sample material. Alternatively,the amount of ethylene may be determined by nuclear magnetic resonance(NMR) using techniques known to one of ordinary skill in the art withthe benefits of this disclosure.

During the production of a polypropylene impact copolymer a certainamount of amorphous polymer is produced. Additionally, the EPR phase ofthe polypropylene impact copolymer is essentially amorphous. Thisamorphous material collectively (i.e., EPR fraction and atacticpolypropylene) is soluble in xylene and is thus termed the xylenesoluble fraction (XS %). In determining the XS %, the polymer isdissolved in hot xylene and then the solution cooled to 0° C. whichresults in the precipitation of the isotactic or crystalline portion ofthe polymer. The XS % is the portion of the original amount thatremained soluble in the cold xylene. Consequently, the XS % in thepolymer is further indicative of the extent of crystalline polymerformed. The total amount of polymer (100%) is the sum of the xylenesoluble fraction and the xylene insoluble fraction. In an embodiment,the polypropylene impact copolymer has a xylene soluble fraction of from8 wt. % to 30 wt. %. Alternatively from 10 wt. % to 25 wt. %,alternatively from 12 wt. % to 20 wt. %. The XS % may be determined inaccordance with ASTM D 5492-98.

In an embodiment, the polypropylene impact copolymer may have a meltflow rate (MFR) or melt flow (MF) of from 1 g/10 min. to 150 g/10 min.,alternatively from 5 g/10 min. to 140 g/10 min., alternatively from 10g/10 min. to 130 g/10 min. Excellent flow properties as indicated by ahigh MFR allow for high throughput manufacturing of molded polymericcomponents. MFR as defined herein refers to the quantity of a meltedpolymer resin that will flow through an orifice at a specifiedtemperature and under a specified load. The MFR may be determined usinga dead-weight piston plastometer that extrudes polypropylene through anorifice of specified dimensions at a temperature of 230° C. and a loadof 2.16 kg in accordance with ASTM Standard Test Method D-1238.

Representative examples of suitable polypropylene impact copolymersinclude without limitation 4920W and 4920WZ, which are impact copolymerresins commercially available from Total Petrochemicals USA Inc. In anembodiment, the polypropylene impact copolymer (e.g., 4920W) hasgenerally the physical properties set forth in Table 1.

TABLE 1 Resin Properties Typical Value ASTM Method Melt Flow, g/10 min.100 D-1238 Density, g/cc 0.905 D-1505 Melting Point, ° C. 160-165 DSCMechanical Properties Tensile strength at Yield, psi (MPa) 3700 (25)D-638 Elongation at Yield, % 6 D-638 Flexural Modulus, psi (MPa) 190,000(1,300) D-790 Notched Izod-ft.lb./in. (J/m)  1.0 (50)  ASTM D-256AThermal Properties Heat Deflection, ° C. 90 D-648

In an embodiment, a process employing a catalyst activator as describedherein may provide an increased production efficiency when compared toan otherwise similar process not employing a catalyst activator. Withoutwishing to be limited by theory, improvements in production efficiencymay be due to increased catalyst system activity over the duration ofthe user-desired process. Without wishing to be limited by theory, aprocess for the production of an impact copolymer employing a reactorsystem comprising more than one reactor type, such as those illustratedin FIGS. 1 and 2 may suffer process inefficiencies due to a decreasedrate of production of the copolymer phase of the impact copolymer. Forexample, during production of a polypropylene impact copolymer, theformation of EPR occurs in the gas phase reactor. The residence time inthe gas phase reactor may be longer than desirable due in part to adecrease in catalyst system activity. For example, a catalyst systemhaving an activity α when used in the initiation of the polymerizationprocess, may have an activity αβ when it enters and is employed in oneor more downstream gas phase reactors where β is greater than 0 but lessthan 1. For example, β is 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.4, 0.3,0.2, or 0.1. The catalyst activator may allow the catalyst system tomaintain some higher threshold level of activity in a downstream gasphase reactor when compared to the activity of an otherwise similarprocess carried out in the absence of a catalyst activator. This higherthreshold activity may result in an increased incorporation of acomonomer, decreased residence time in the copolymer producing reactoror both.

In an embodiment, a process (e.g., impact copolymer production process)employing a catalyst system (e.g., ZN, cocatalyst, external electrondonor) when contacted with a catalyst activator through distributedadditions as described herein may show an increase in the total polymeryield and/or an increase in the polymer yield rate of greater than 5%,alternatively greater than 10%, alternatively greater than 20%,alternatively greater than 30% when compared to an otherwise similarprocess carried out using an alternate methodology. As will beunderstood by one of ordinary skill in the art with the benefits of thisdisclosure, the absolute polymer yield rates and polymer yields willdepend on a variety of factors (e.g., the nature of the polymerproduced, the reaction conditions, type of catalyst) and will varydepending on such factors. Furthermore, a process (e.g., impactcopolymer production process) employing a catalyst system when contactedwith a catalyst activator through distributed additions as describedherein may show an increased comonomer incorporation for a similarresidence time in the gas phase reactor of 4 wt. %, alternatively 2 wt.%, alternatively 1 wt. % based on the total weight of the compositionwhen compared to an otherwise similar process not employing themethodologies disclosed herein. In an embodiment, a process (e.g.,impact copolymer production process) employing a catalyst system whencontacted with a catalyst activator through distributed additions asdescribed herein may show an increase in the gas phase reactor yield offrom 5% to 30% when compared to an otherwise similar process notemploying the methodologies disclosed herein. The process may be furthercharacterized by an increase in the process efficiency of greater than5%, alternatively greater than 7%, alternatively greater than 10% whencompared to an otherwise similar process not employing the methodologiesdisclosed herein.

EXAMPLES

The following examples are given as particular embodiments of thedisclosure and to demonstrate the practice and advantages thereof. It isunderstood that the examples are given by way of illustration and arenot intended to limit the specification.

Example 1

Experiments were conducted to assess the effect on catalyst activity ofthe addition of extra TEAl (1 mmol) at various points in an impactcopolymer (ICP) production process. The catalyst was ZN M1, a commercialheterogeneous Ziegler-Natta catalyst from Basell, containing about 2.4wt % Ti and 18-19 wt % Mg. Referring to FIG. 1, in the ICP productionprocess, the extra TEAl was added up front in the initial feed asindicated for example by reference arrow 501 and hereinafter referred toas point 1, after the baby loop (e.g., after the prepolymerization) asindicated for example by reference arrow 560 and hereinafter referred toas point 2, in the course of the bulk polymerization for times rangingfrom 30 to 50 min to simulate the end of the first loop as indicated forexample by reference arrow 570 and hereinafter collectively referred toas point 3, at the end of the bulk polymerization stage to simulate theend of the second loop as indicated for example by reference arrow 580and hereinafter referred to as point 4, and directly in the GPR asindicated for example by reference arrow 540 and hereinafter referred toas point 5. The addition of extra TEAl at points 2 and 3 was conductedat 70° C. under nitrogen pressure. When the extra TEAl additionsoccurred at point 4, a part of the liquid propylene was flared (thepressure was decreased from 485 to 200 PSI) and the remaining liquid C₃was used to stir the fluff for a few minutes (3 min) with extra TEAl,added at room temperature under nitrogen pressure. Then, the remainingliquid C₃ was flared and the gas phase copolymerization portion of theprocess was conducted. General laboratory process conditions were asfollows: bulk polymerization at 70° C. for 1 h, 1 mmol TEAl, CMDS asexternal donor (0.1 mmol giving an initial Al/Si ratio of 10). The GPRpolymerizations were carried out under a constant flow of gases at 0.08L/min hydrogen, 3.15 L/min ethylene and 3.85 l/min propylene. When extraTEAl was added at point 5, the liquid propylene was flared and extraTEAl was added in the GPR at room temperature. Then, the temperature andthe pressure were respectively increased up to 75° C. and 135 PSI, andthe gas phase copolymerization portion of the process was run for 25minutes. Most of the polymerization experiments were run several timesto ensure reproducibility and Table 2 gives average results for theprocess conditions where BD is the bulk density of the polymer fluff ing/ml, bulk yield refers to the yield of polypropylene homopolymer andICP yield refers to the yield of EPR.

TABLE 2 Estimated Wt. Total Bulk/Gas phase % MF Number yield prod.balance C2 XS dg/10 BD # of trials Comments (g) (%) (IR) % min g/ml 1 12Standard Bulk Run 203 — — 2.6 28 0.42 Standard bulk run 2 4 Standard ICP237 19 8.4 13.3 16 0.45 3 1 1 mmol extra TEAl at the 312 24 10.7 15.7 180.45 beginning (=in the baby loop) 4 3 1 mmol extra TEAl at 70° C. in282 22 10.4 15.2 17 0.46 bulk (=after baby-loop) 5 1 1 mmol extra TEAl X= 30 280 17 7.7 16.6 15 0.44 after X min in bulk min 6 (=after the firstloop) X = 40 270 19 8.6 17.0 14 0.44 min 7 X = 50 282 21 9.4 15.3 150.46 min 8 3 1 mmol extra TEAl at the end of 250 23 10.3 15.9 17 0.46Bulk (=after the second loop) 9 4 1 mmol extra TEAl in the GPR 257 2310.2 16.9 21 0.47 (=in the gas phase portion) 10 1 Two extra TEAladditions 264 22 9.8 18.2 16 0.46 0.5 mmol in bulk after 30 min and 0.5mmol in the GPR

The polymerization results are compared to a standard ICP run shown inRow 2 of Table 2. As seen from the above results, addition of extra TEAl(1 mmol) increases the total polymer yield in the range 5-30%, the totalethylene content in the range 8.6-10.7% (as measured by FTIR) and theBulk/Gas phase productivity balance in the range 19-24%. It can also benoticed that extra TEAl addition results in an increase in the xylenesoluble (i.e., EPR) content (+1.9-3.7%), which is in agreement with ahigher total C₂ content in the ICPs. In terms of melt flows and bulkdensities, both are not greatly affected by an extra TEAl addition andare similar to those obtained with a standard ICP run.

The particle size distributions (PSD) of the ICPs were obtained viasieve analyses of the fluff samples as shown in FIG. 3. In terms of PSD,the distributions are similar to each other with no indication ofpolymer fines formation, although addition of more TEAl up front yieldsa slightly higher content of smaller particles. The average fluffparticle sizes (D50) for the ICPs are in the range 1460-1740 microns vs.1620 microns for a standard ICP.

Based on the laboratory results, it appears that addition of more TEAlup front gives the highest GPR reactivity enhancement with respect tothe total polymer yield (+30%), to the Bulk/Gas phase productivitybalance (24%) and to the total C₂ content (10.7%) Further, the additionof extra TEAl at other distributed points in the process also giveshigher yields and C₂ contents than the control sample. In the case ofextra TEAl addition in the course of the bulk, it was observed that theethylene incorporation appears to be lower than expected despite thefact that the total polymer yields and the XS contents have increased.Moreover, the results also show that addition of more TEAl after thebaby loop (e.g., FIG. 1, 560) and at the end of the bulk (FIG. 1, 580)yielded ICPs with 10.2-10.3% of ethylene. From the results, it can beconcluded that the ethylene contents are likely underestimated whenextra TEAl is added in the course of the bulk and may be closer to10.2-10.3% (IR).

An additional trial was carried out using a double extra TEAl additionby splitting 1 mmol of extra TEAl into 0.5 mmol extra TEAl in bulk and0.5 mmol extra TEAl in the GPR to assess the effect of multipleadditions vs. a single one on the GPR activity enhancement, as seen inTable 2, row 10. The results show that adding 0.5 mmol of extra TEAl twotimes in the process increases the Bulk/Gas phase productivity balanceof the catalyst, but there is no more benefit compared to a single extraTEAl addition conducted with 1 mmol of TEAl.

The results indicate that an extra TEAl addition increases the ZN M1catalyst activity leading to higher polymer yields and higher total C₂contents. Without wishing to be limited by theory, the benefit effect ofextra TEAl addition may be due to the increase in the Al/Ti ratio, whichis known to control the Ziegler-Natta catalyst productivity. Moreover,an addition of more TEAl in the polymerization medium may decrease thepoisoning effect of moisture or other polar impurities that could bepresent in the monomers.

Example 2

An approach based on a two-step process modification was investigated toattempt to increase the Bulk/Gas phase productivity balance of an ICPproduction process employing a ZN catalyst, the Basell ZNM1 catalyst.Specifically, the effect of adding extra TEAl or TEAl/CMDS at the end ofthe bulk (FIG. 1, point 4) or in the GPR (FIG. 1, point 5) when lowerinitial TEAl or TEAl/CMDS amounts were used to run the bulk phase wasassessed. Two approaches were investigated. In the first approach, Trial1, both the initial TEAl and CMDS concentrations were decreased bykeeping constant the Al/Si ratio of 10. In the second approach, Trial 2,only the initial TEAl concentration was decreased. The initial CMDSamount was kept constant to 0.1 mmol, involving a decrease of the Al/Simolar ratio for the experiments.

Specifically, the reaction conditions for bulk polymerization: liquidC₃=740 g; ZN M1 catalyst: 10 mg; H₂: 0.4 mol %; T=70° C.; 1 hour and inthe GPR: C₂=3.15 L/min; C₃=3.85 L/min; H₂=0.08 L/min; 75° C.; 25 min.The bulk polymerizations were conducted at 70° C. for 1 h by varying theinitial TEAl or TEAl/CMDS amounts. The GPR was run at 135 psi and 75° C.for 25 min. The extra TEAl or TEAl/CMDS additions occurred either at theend of the bulk polymerization stage or in the GPR. For each experiment,the total TEAl amount is 2 mmol and the total CMDS amount is 0.1 mmol.Depending on the initial TEAl/CMDS amounts used to start the bulk phase,the addition of extra TEAl or extra TEAl/CMDS was done in order to reacha total TEAl concentration of 2 mmol and a total CMDS concentration of0.1 mmol. The results of these runs are given in Table 3, FIG. 4 forTrial 1 and FIG. 5 for Trial 2.

TABLE 3 Initial Extra Estimated XSAl TEAl/CMDS ratio TEAl/CMDS Totalbulk/gas phase (EPR MF in bulk addition yield prod. balance Wt. %fraction) dg/10 BD (mmol/mmol) (mmol/mmol) (g) (%) C2 XS % % min g/ml1.0/0.1 mmol Standard bulk run 203 NA* NA 2.6 NA 28 0.42 Al/Si = 10Standard ICP 237 19 8.4 13.3 13.4 16 0.45 IR 0.5/0.05 mmol 1.5/0.05 24228 12.7 18.7 16.5 19 0.44 Al/Si = 10 at the end of bulk NMR Trial 11.5/0.05 205 22 10.0 18.7 16.5 24 0.44 in the GPR IR 0.8/0.08 mmol1.2/0.02 280 24 10.8 17.2 17.9 15 0.45 Al/Si = 10 at the end of bulk NMRTrial 1 1.2/0.02 300 21 9.6 16.0 ND 19 0.46 in the GPR IR 0.5/0.1 mmol1.5/0.0 110 21 9.3 7.0 ND 16 0.42 Al/Si = 5 in the GPR IR Trial 20.8/0.1 mmol 1.2/0.0 261 28 12.8 17.0 17.8 15 0.44 Al/Si = 8 at the endof bulk NMR Trial 2 1.2/0.0 226 24 11.1 17.6 ND 15 0.43 in the GPR NMRND = not determined

XSAl refer to the xylene solubles-acetone insoluble material in thepolymer which is characteristically the EPR portion of the polypropyleneimpact copolymer. The xylene solubles content of the polymer may bedetermined as described previously herein. The resulting xylene solublematerial may be further contacted with acetone and the material that isinsoluble in acetone measured. Based on the laboratory results, themodifications conducted appear to increase the GPR reactivity givingBulk/Gas phase productivity balances in the range 21-28%, total C₂contents increased up to 12.8% as determined by NMR and higher totalpolymer yields. All the modified runs lead to higher fractions of XS andXSAl (EPR fraction) compared to a standard ICP, which is also inagreement with a higher GPR reactivity. Again, the bulk densities andthe melt flow values for the polymer samples remained almost constant.

From the results, it can also be seen that the total polymer yield andthe total C₂ content in the ICPs depend on the initial TEAl/CMDSconcentration (which fixed the amount of extra TEAl/CMDS added).Referring to Table 3, by using a low initial TEAl/CMDS ratio (0.5/0.05)and by adding extra TEAl/CMDS (1.5/0.05 mmol), the total polymer yieldwas lower or similar to that obtained for a standard ICP run using only1 mmol of TEAl and 0.1 mmol of CMDS. However, the ICPs contained asignificantly higher total C₂ content up to 12.7% by NMR. By increasingthe initial TEAl/CMDS mixture from 0.5/0.05 to 0.8/0.08, the totalpolymer yield increased in the range of 15-46%, depending on where theextra TEAl/CMDS addition was performed (at the end of the bulkpolymerization stage or in the GPR), but the ethylene incorporationappeared to be lower (10.8 vs. 12.7% by NMR). However, the total C₂content was still higher than that of a standard ICP. Based on theresults, an initial TEAl/CMDS mixture of 0.8/0.08 followed by an extraTEAl/CMDS addition (1.2/0.02) gave a good productivity/C₂ incorporationbalance and enhanced the GPR activity.

Referring to Table 3, it appeared that the effect of decreasing theinitial TEAl amount at a constant CMDS amount (0.1 mmol) on the GPRreactivity strongly depended on the initial TEAl amount. By using amixture of TEAl/CMDS (0.5/0.1) to run the bulk phase, the total polymeryield was divided by a factor of 2 and the C₂ content was only slightlyhigher than that of a standard ICP (9.3 vs. 8.4% IR). Without wishing tobe limited by theory, a strong poisoning effect of the active sites bythe external donor may account for the results. By increasing theinitial TEAl/CMDS mixture from 0.5/0.1 to 0.8/0.1, the total polymeryield was 10% higher than that of a standard ICP, the Bulk/Gas phaseproductivity balance reached 28% and the total C₂ content was as high as12.8% (NMR). Based on the results, an initial TEAl/CMDS mixture of0.8/0.1 followed by an extra TEAl addition (1.2 mmol) gave a goodproductivity/C₂ incorporation balance and enhanced the GPR activity.From these results, it also appeared that the highest ethyleneincorporation occurs when extra TEAl is added at the end of the bulk.

Referring to FIG. 1, the results further indicate that extra TEAladdition (1 mmol) at some defined points in the process (in the babyloop 510, after the baby loop 560, after the first loop 570, after thesecond loop 580, and in the GPR 540) increased the total polymer yield,the Bulk/Gas phase productivity balance and the total C₂ content in theICPs without changing the ICP PSD, melt flows, or the bulk density.Addition of extra TEAl up front (in the baby loop 510) appeared to givethe highest GPR activity enhancement. Other selected processmodifications were performed by splitting a total TEAl amount of 2 mmoland a total CMDS amount of 0.1 mmol. The results show that the use of aninitial TEAl/CMDS mixture (0.8/0.08) followed by an extra TEAl/CMDS(1.2/0.02) addition at the end of the bulk or the use of an initialTEAl/CMDS mixture (0.8/0.1) followed by an extra TEAl addition (1.2mmol) at the end of the bulk increased the GPR reactivity leading to agood productivity/ethylene incorporation balance.

Example 3

Experiments were carried out in order to assess the effect on the GPRactivity of the addition of extra TEAl (1 mmol) at 70° C. in the courseof the bulk polymerization stage for times ranging from 0 min to 50 min.Extra TEAl (1 mmol) was added in the bulk phase at 70° C. under nitrogenpressure. The bulk polymerizations were conducted at 70° C. for 1 h,using 1 mmol TEAl, 0.1 mmol CMDS as the external donor, (initialAl/Si=10), Liquid C3=740 g; ZN M1 catalyst: 10 mg; H₂: 0.4 mol %; whilethe GPR conditions were C₂=3.15 L/min; C₃=3.85 L/min; H₂=0.08 L/min; 75°C.; 25 min. The GPR was run at 135 psi and 75° C. for 25 min. There werefour ICPs produced, ICP1, ICP2, ICP3 and ICP4 which were compared totheir homopolymer polypropylenes PP1, PP2, PP3, and PP4. The polymerproperties are presented in Table 4 where aR indicates the estimatedbulk phase productivity balance.

TABLE 4 Time of Bulk Total GPR GPR % MF TEAl yield yield yield Prod.activity C2 dg/10 % BD # Run addition (g) (g) (g) g/g g/g/h aR (IR) minXS g/ml 1 PP — 194 194 — 19400 — — — 27 2.0 0.42 2 ICP — 194 214 2021400  4800  9 7.2 25 12.0 0.46 3 PP1 0 236 236 — 23600 — — — 29 2.00.44 4 ICP1 0 236 303 67 30300 16100 22 9.7 16 16.2 0.46 5 PP2 30 218218 — 21800 — — — 20 1.8 0.41 6 ICP2 30 218 280 62 28000 14900 22 7.7 1516.6 0.44 7 PP3 40 208 208 — 20800 — — — 21 2.0 0.41 8 ICP3 40 208 27062 27000 14900 23 8.6 14 17.0 0.44 9 PP4 50 192 192 — 19200 — — — 28 1.80.41 10 ICP4 50 192 282 90 28200 21600 32 9.4 15 15.3 0.46

The results demonstrate, an extra TEAl addition in the bulkpolymerization stage of the process increases the bulk yield, the totalyield and the GPR yield compared to the standard PP and ICP runs. Fromthe results, it appeared that the GPR yield was not greatly affected bytime of TEAl addition. In contrast, the bulk yield depended on the timeof TEAl addition, with the yield decreasing as extra TEAl was addedlater in the process. This result is not surprising since it is knownthat the catalyst productivity increases with the Al/Ti (and Al/Si)molar ratio. Furthermore, the results demonstrate that the addition of 1mmol of extra TEAl in the bulk, resulting in an increase in the Al/Siratio from 10 to 20, gave higher catalyst productivities in the bulkphase. For example the ICP prepared in the absence of extra TEAlresulted in an aR of 9 (see Row 2) whereas the addition of extra TEAlgave an aR ranging from 22 to 32 (see Rows 4,6,8) respectively. FIG. 6shows the bulk yields vs. time when an Al/Si ratio of 20 was used in thebulk phase. As shown, the longer the time with the Al/Si ratio of 20(i.e., after extra TEAl addition), the higher the bulk yields. Based onthe bulk yields, the Basell ZN M1 catalyst productivity in bulk can beimproved by 20% by increasing the Al/Si ratio from 10 to 20.

Additionally, the higher C₂ contents obtained by performing extra TEAladditions in the bulk (7.7-9.7 vs. 7.2%) confirm that the extra TEAladdition in the bulk had a beneficial effect on the GPR yield. Finally,it was observed that the polymer properties in terms of bulk density andmelt flows were not greatly affected by performing extra TEAl additions.Moreover, the wt. % XS were higher with extra TEAl additions which arein agreement with a higher GPR reactivity. The results demonstrate thatthe addition of TEAl at different times in the bulk phase resulted in agreater ethylene incorporation.

Example 4

Effect of the concentration of extra TEAl added during the bulkpolymerization stage on the bulk/gas phase productivity balance wasinvestigated. Specifically, the amount of extra TEAl added in bulk wasvaried to assess its effect on the GPR activity enhancement. The extraTEAl addition was performed after 30 min in bulk, at 70° C. for TEAlamounts ranging from 0.5 mmol to 1.0 mmol. Specifically, the bulkpolymerization conditions were: liquid C₃=740 g; ZN M1 catalyst: 10 mg;TEAl: 1 mmol; CMDS: 0.1 mmol; H₂: 0.4 mol %; T=70° C.; 1 hour and theGPR conditions were: C₂=3.15 L/min; C₃=3.85 L/min; H₂=0.08 L/min; 75°C.; 25 min. Extra TEAl (1 mmol) was added in the bulk phase at 70° C.under nitrogen pressure. The polymer properties are given Table 5.

TABLE 5 Bulk/ Total GPR GPR TEAl yield yield yield Prod. activity % C2MF % BD Run amount (g) (g) (g) g/g g/g/h IR (IR) dg/10 min XS g/ml PP —194 194 — 19400 — — — 27 2.0 0.42 ICP — 194 214 20 21400  4800  9  7.225 12.0 0.46 PP1 0.5 210 210 — 21000 — — — 24 2.0 0.42 ICP1 0.5 210 29080 29000 19200 28  9.8 13 16.4 0.46 PP2 0.8 212 212 — 21200 — — — 25 2.10.42 ICP2 0.8 212 294 82 29400 19700 28 10.8 14 17.0 0.46 PP3 1.0 218218 — 21800 — — — 20 1.8 0.41 ICP3 1.0 218 280 62 28000 14900 22 7.7 1516.2 0.44$R = \frac{{GPR}\mspace{14mu}{yield}}{{Total}{\mspace{11mu}\;}{yield}}$

The results demonstrate higher bulk yield, higher total yield, andhigher GPR yields were obtained by performing an extra TEAl addition inthe course of the bulk polymerization. The results also show that theamounts of polymer formed were similar regardless of the amount of extraTEAl added in the range of 0.5-1.0 mmol. Therefore, for this process, itwas not necessary to work with an extra TEAl amount higher than 0.5 mmolto get the highest bulk/gas phase productivity balances. The resultsindicated that the melt flows of the polymers, the bulk density and thexylene soluble contents were not greatly affected by the amount of extraTEAl addition. In terms of ethylene incorporation, addition of more TEAlin bulk leads to ICPs with higher ethylene contents (up to 10.8%), whichis in agreement with a GPR activity enhancement. Based on the results,it seems possible to increase the bulk/gas phase productivity balanceand the ethylene content in the ICPs via addition of extra TEAl in theICP process. Although it is difficult to determine accurately how muchthe activity is increased in the GPR by performing extra TEAl additionsin bulk, the higher C₂ contents in the ICPs confirm again that theseprocess modifications increase the GPR reactivity.

Example 5

The effect of reducing the initial amount of cocatalyst on the bulk/gasphase productivity was investigated. Bulk polymerizations (each reactionwas repeated four times) were carried out as follows: liquid C₃=740 g;catalyst: ZN M1; CMDS: 0.1 mmol; H₂: 0.4 mol %; T=70° C.; 1 hour. GPR:C2=3.15 L/min; C₃=3.85 L/min; H₂=0.08 L/min; 75° C.; 25 min. Then,laboratory ICP experiments were conducted and an additional amount ofTEAl was added after the 2nd loop (FIG. 1, 580) or directly in the GPR(FIG. 1, 590) as indicated to assess the effect on the GPR activityenhancement. For these experiments the total TEAl level in the processwas in the range 1.0-1.2 mmol. The amounts of reactants and results aregiven in Table 6 and are compared to those obtained using standardconditions for ICP production.

TABLE 6 Reference Selected Process Modifications PP ICP PP 4 RUN AverageAverage runs ICP Run 1 ICP Run 2 ICP Run 3 ICP Run 4 Catalyst (mg) 10 1012.5 12.5 12.5 12.5 12.5 Initial TEAl 1.0 1.0 0.6 0.6 0.6 0.6 0.6 (mmol)Initial CMDS 0.1 0.1 0.1 0.1 0.1 0.1 0.1 (mmol) Initial Al/Ti 200 200 9696 96 96 96 Complement — — — 0.6 mmol 0.6 mmol in 0.4 mmol 0.4 mmol inTEAL (mmol) after 2nd loop the GPR after 2nd loop the GPR Total Al/Ti200 200 96 192 192 160 160 Bulk Yield (g) 203 203 203 203 203 203 203ICP Yield (g) — 237 — 252 284 245 282 Estimated GPR — 19 — 23 26 21 24balance % C2 (IR) — 8.4 — 10.5 11.5 9.5 10.9 XS % 2.6 13.3 2.0 — — —16.1 MF g/10 min 28 16 23 16 9 12 5 Bulk Density g/ml 0.42 0.45 0.420.46 0.46 0.46 0.46

A decrease in the initial amount of TEAl by 40% from 1.0 to 0.6 mmolwith the standard catalyst load (10 mg of ZN M1) drops catalyst activityin bulk by ˜35%. With the aim of maintaining the production rate in theloops (˜200 gr bulk yield), more catalyst was added in the process; acatalyst load of 12.5 mg was found to be suitable to meet the processobjectives.

From the above results, it can be seen that by dropping the initialamount of TEAl by 40% and increasing the initial amount of catalyst by25%, a decrease in the catalyst activity in bulk of 20% (16.2 vs. 20.3Kg/g/h) was observed without significantly affecting the polymerproperties in terms of MF (28 vs. 23 g/l 0 min), bulk density (0.42g/ml) and particle size distribution.

FIG. 7 shows the PP particle size distribution (PSD) obtained via sieveanalyses of the fluff samples. As seen, even with more catalyst and witha lower bulk activity, the average fluff particle size (D50) is similarto that of a standard ICP, i.e., 1350 vs. 1450 microns. Also, bydecreasing the initial amount of TEAl from 1.0 to 0.6 mmol and bykeeping constant the external donor amount (i.e., CMDS) at 0.1 mmol, theAl/Si ratio decreases from 10 to 6, thereby allowing for better XScontrol (2.0 vs. 2.6%). Further, from the laboratory ICP results, it canbe seen that these selected process modifications increase the total ICPyields, the total C2 content in the ICPs (9.5-11.5 vs. 8.4%) and thebulk/gas phase productivity balances in the range 21-26% vs. 19%. Theincrease of the XS % from ˜13 to ˜16% is also consistent with a higherGPR reactivity. By increasing the complementary TEAl amount from 0.4 to0.6 mmol, the total C2 content in the ICPs is ˜1% higher regardless ofwhere the TEAl is added in the process. The higher the amount ofcomplementary TEAl, the higher the GPR activity enhancement. Inaddition, the larger increases in production efficiencies (e.g., totalICP yields) seem to be obtained by adding the TEAl directly in the GPRvs. after the 2nd loop.

The particle size distributions of ICPs are presented in FIG. 8. Thedistributions are similar to that observed with the standard ICPproduction method, with no indication of polymer fines formation. TheD50s are similar to that obtained for the standard ICP production methodi.e., ˜1550 vs. ˜1620 microns. To conclude, these selected processmodifications based on extra catalyst and on the splitting of the normalTEAl level between the baby loop and the GPR (or after the 2nd loop)increased the reactivity of the ZN M1 in the GPR reactor.

Example 6

The effect of varying the nature of the catalyst on the catalystactivator was investigated. Two catalysts were compared in thisexperiment. ZN M1, described previously in Example 1, and ZN 128M, adiether-based catalyst commercially available from Basell. The catalystswere used in the production of an ICP under a standardized set ofconditions. The bulk reaction conditions were liquid propene: 740 g,external donor: CMDS, 70° C. in bulk. GPR conditions: C2: 3.15 L/Min,C3: 3.85 L/Min (R=0.45), H2: 0.08 L/Min for ZN M1, C2: 2.4 L/Min, C3:3.6 L/Min (R=0.40), H2: 0.08 L/Min for ZN 128M. The results of thesereactions are presented in Table 7.

TABLE 7 RUN PP Average ICP Average PP Run 9 ICP Run 5 Catalyst ZN M1 ZNM1 ZN 128M ZN 128M Catalyst (mg) 10 10 3 3 Initial TEAl (mmol) 1.0 1.01.0 1.0 Initial CMDS 0.1 0.1 0.015 0.015 (mmol) Initial Al/Ti 200 200456 456 Hydrogen (mol %) 0.40 0.40 0.68 0.68 Bulk Yield (g) 203 — 193 —Bulk Activity 20.3 — 64.3 — (kg/g/h) ICP Yield (g) — 237 — 231 EstimatedGPR — 19 — 15 Balance (%) % C2 (IR) — 8.4 — 5.8 XS % 2.6 13.3 3.2 6.8 MF(g/10 min) 28 16 178 127 Bulk Density (g/ml) 0.42 0.45 0.41 0.46

The results demonstrate that the ZN 128M exhibits a relatively lowability to incorporate ethylene for the production of high MF ICP resinsi.e., ˜6% total C2 at an ICP MF of 127 g/10 min. Further, under standardreaction conditions (i.e., 1 mmol TEAl), the ZNM1 catalyst produced anICP containing 8.4 wt. % ethylene.

Example 7

ICP experiments were also conducted with the two catalysts by usingextra catalyst/split TEAl to assess the effect on the GPR activityenhancement. In the case of ZN M1, the catalyst load was increased by˜25% when the TEAl level up front was decreased from 1 to 0.6 mmol, tomaintain the solids level constant in the loops. Subsequently, thecomplement of TEAl to reach the normal TEAl level in the process (1mmol) was added after the 2nd loop (FIG. 1, 580) or in the GPR (FIG. 1,590) for activating the catalyst for the gas phase reaction. In the caseof ZN 128M, the extra catalyst load was fixed at 15%, the initial TEAlamount at 0.6 mmol and the total TEAl level at 1.2 mmol. The bulkreaction conditions were: liquid propylene: 740 g, external donor: CMDS,70° C. in bulk. GPR conditions: C2: 3.15 L/Min, C3: 3.85 L/Min (R=0.45),H2: 0.08 L/Min, 75° C. for ZN M1, C2: 2.4 L/Min, C3: 3.6 L/Min (R=0.4),H2: 0.08 L/Min, 75° C. for ZN 128M. Extra catalyst: 16% extra catalystfor ZN 128M. The results are presented in Table 8 and FIGS. 9 and 10.

TABLE 8 PP ICP Run ICP Run PP Run ICP Run ICP Run RUN Reference 6 7 8 910 Catalyst ZN M1 ZN M1 ZN M1 ZN ZN ZN 128M 128M 128M Catalyst Amount(mg) 12.5 12.5 12.5 3.5 3.5 3.5 Initial TEAl amount 0.6 0.6 0.6 0.6 0.60.6 (mmol) Initial CMDS (mmol) 0.1 0.1 0.1 0.02 0.02 0.02 Initial Al/Ti96 96 96 235 235 235 Hydrogen mol % 0.40 0.40 0.40 0.68 0.68 0.68Complement of TEAl — 0.4 mmol 2nd 0.4 mmol — 0.6 mmol 2nd 0.6 mmol loopGPR loop GPR Total Al/Ti 96 160 160 235 469 469 Bulk Yield (g) 203 — —198 — — Bulk Activity (Kg/.g./h) 16.2 — — 56.6 — — ICP Yield (g) — 248282 — 240 170 Estimated GPR balance — 21 24 — 16 19 (%) % C2 (IR) — 9.510.9 — 6.5 7.7 XS % 2.0 14.1 16.1 3.8 14.3 13.8 MF (g/10 min) 2.1 12 5268 181 216 Bulk Density (g/ml) 0.42 0.46 0.46 0.40 0.46 0.46

As seen from the results, using more catalyst in the baby loop(˜15-25%), (FIG. 1, 510) with less TEAl (40-50%), decreases the bulkactivity by approximately 20% for ZN M1, and approximately 12% for ZN128M without greatly affecting the PP properties in terms of XS and BD.However, ZN 128M yields PP having significantly higher MF (268 vs. 178g/10 min), suggesting that the use of a low TEAl level for the activesites formation modifies the hydrogen response of the ZN 128Mdiether-based catalyst.

Referring to FIGS. 9 and 10, it can be seen that the processmodifications based on extra catalyst/split TEAl clearly increased theGPR reactivity of the ZN M1 and ZN 128M catalysts giving higher Bulk/Gasphase productivity balances (+1-5%), higher total C2 contents (+2% inaverage) and higher XS levels (˜X1.3 for ZN M1 and ˜X2.8 for ZN 128M).Again with ZN 128M, the ICP MFs are shifted to higher values than thoseexpected (˜200 vs. 130 g/10 min) which without wishing to be limited bytheory may be due to the low initial amount of TEAl. However, the resultobtained with ZN 128M shows that by adjusting the hydrogen level themethod can successfully be extended to diether-based catalysts that aretypically gas phase limited for the production of high MF ICP resins.Moreover, the results demonstrate the highest GPR reactivity enhancementwas obtained by adding the complement of TEAl directly into the gasphase reactor when compared to the reactivity obtained if the TEAl isadded after the 2nd loop.

While various embodiments have been shown and described, modificationsthereof can be made by one skilled in the art without departing from thespirit and teachings of the disclosure. The embodiments described hereinare exemplary only, and are not intended to be limiting. Many variationsand modifications of the embodiments disclosed herein are possible andare within the scope of the disclosure. Where numerical ranges orlimitations are expressly stated, such express ranges or limitationsshould be understood to include iterative ranges or limitations of likemagnitude falling within the expressly stated ranges or limitations(e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than0.10 includes 0.11, 0.12, 0.13, etc.). Use of the term “optionally” withrespect to any element of a claim is intended to mean that the subjectelement is required, or alternatively, is not required. Bothalternatives are intended to be within the scope of the claim. Use ofbroader terms such as comprises, includes, having, etc. should beunderstood to provide support for narrower terms such as consisting of,consisting essentially of, comprised substantially of, etc.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an embodiment ofthe present disclosure. Thus, the claims are a further description andare an addition to the embodiments disclosed herein. The discussion of areference herein is not an admission that it is prior art to the presentdisclosure, especially any reference that may have a publication dateafter the priority date of this application. The disclosures of allpatents, patent applications, and publications cited herein are herebyincorporated by reference, to the extent that they provide exemplary,procedural or other details supplementary to those set forth herein.

What is claimed is:
 1. A method comprising: preparing a multi-componentcatalyst system comprising a catalyst and a cocatalyst; and adjusting alevel of at least one component of the multi-component catalyst systemto maintain a user-desired level of catalyst activity throughout apolymerization process; wherein the at least one component comprises acatalyst activator, and wherein the catalyst activator comprises thecatalyst.
 2. The method of claim 1, wherein the catalyst activatorfunctions to maintain the catalyst activity to a user-desired thresholdlevel throughout the polymerization process.
 3. The method of claim 1,wherein the multi-component catalyst system comprises an externalelectron donor.
 4. The method of claim 1, wherein the multi-componentcatalyst comprises a Ziegler-Natta catalyst, a metallocene catalyst, orcombinations thereof.
 5. The method of claim 1, wherein the cocatalystcomprises an organoaluminum compound.
 6. The method of claim 5, whereinthe organoaluminum compound comprises tri ethyl aluminum,tri-isobutylaluminum, diethylaluminum chloride, diethylaluminum hydride,methylalumoxane, tri-isobutylaluminum, or combinations thereof.
 7. Themethod of claim 3, wherein the electron donor comprises an externalelectron donor.
 8. The method of claim 7, wherein the external electrondonor comprises cyclohexylmethyl dimethoxysilane, dicyclopentyldimethoxysilane, diisopropyl dimethoxysilane, or combinations thereof.9. The method of claim 1, wherein multi-component catalyst systemfunctions as a polymerization catalyst.
 10. The method of claim 1,wherein the multi-component catalyst system is introduced to a firstlocation in a reaction zone and the catalyst activator is introduced toa second location in the reaction zone.
 11. The method of claim 10,wherein the reaction zone comprises multiple reactor types.
 12. Themethod of claim 1, wherein the polymerization process is apolymerization process for the production of a polypropylene impactcopolymer.